1. Field of the Invention
The present invention relates to mobile radio communications systems employing orbiting satellites or relay stations, particularly, to a communications system and method for facilitating satellite communications for users of terrestrial mobile telephony systems employing a variety of interface standards, more particularly, to a communications system and method where the satellite uses at least one air interface standard which is closely related to at least one of the terrestrial interface standards.
2. Background and Objects of the Present Invention
The evolution of wireless communication over the past century, since Guglielmo Marconi's 1897 demonstration of radio's ability to provide continuous contact with ships sailing the English Channel, has been remarkable. Since Marconi's discovery, new wireline and wireless communication methods, services and standards have been adopted by people throughout the world. This evolution has been accelerating, particularly over the last ten years, during which the mobile radio communications industry has grown by orders of magnitude, fueled by numerous technological advances that have made portable radio equipment smaller, cheaper and more reliable. The exponential growth of mobile telephony will continue to rise in the coming decades as well, as this wireless network interacts with and eventually overtakes the existing wireline networks.
One area of current growth in mobile telephony is in mobile satellite systems where a mobile user's signal is relayed by an orbiting satellite, e.g., in geostationary orbit, to another user, as will be explained in more detail hereinafter. Examples of global satellite systems currently under development are Iridium, Globalstar and ICO Global Communications, Ltd. Examples of regional satellite systems also under development include the Association of SouthEast Asian Nations' (ASEAN) Cellular Satellite (ACeS) system, APMT, Thuraya, EAST and several others. At present, the prevailing view in the design of these satellite systems is to use air interface standards which are proprietary to each system and are thus not compatible with other standards.
In view of the aforedescribed exponential growth of the mobile telephony business, particularly in view of the numerous existing and emerging terrestrial cellular and Personal Communications Services (PCS) standards throughout the world, e.g., the Global System for Mobile (GSM) communications, the Digital Advanced Mobile Phone System (D-AMPS), Pacific Digital Cellular (PDC) and Code Division Multiple Access (CDMA) among others, the proprietary standard approach for satellite telecommunications systems is clearly a doubtful course to take in future development.
Applicant is a co-author of an article entitled "Dual-Mode Cellular/Satellite Hand-Held Phone Technology", in Wescon 96 Conference Record, pages 206-222, Oct. 22-24, 1996, in which he demonstrated that a satellite air interface that is modeled closely on, i.e., is a derivative of, an existing terrestrial or PCS standard, e.g., GSM, achieves significant technological and financial synergies. For example, in a satellite system using dual-mode radiotelephones, e.g., having a first terrestrially-based mode, e.g., GSM, and a second satellite-based mode, e.g., ACeS, which is patterned after GSM, circuitry reuse within the dual-mode radiotelephones and the satellite system infrastructure permits technological synergies between the ground-based satellite system equipment and corresponding GSM networks, as well as financial synergies for customers, i.e., a dual-mode radiotelephone having attractive cost, size and weight considerations.
It is, accordingly, an object of the present invention to provide a satellite system, including satellite transponder and gateway apparatus, that utilizes the technology and standards of one or more terrestrially-based cellular systems.
It is a more particular object of the present invention to utilize at least one air interface standard in the satellite that is derived from at least one of the terrestrially-based air interface standards used in customers' mobile terminals.